Custom thumbnails are possible: https://forums.opera.com/post/41282

Let casual users play with a database and you'll get even more problems. :p

A nice UI to join an image to an URL would be way better than those 6 steps using a third party software to edit a database's table.

So +1 for thumbnails customisation. (or at least an UI allowing to easily do it)

I've been testing the last Opera Next (v.24) and one thing (among others being integrated) that really bothers me is having a tab for the downloads manager.

I think an option allowing to put it in a side panel could be good. That way tabs space is only for web pages and it avoids searching for the downloads tab in the middle of many others. It also allows to keep an eye on downloads while browsing without exporting the downloads tab in an other window or clicking on the download shortcut next to the address bar.

It might probably be a huge work on Opera's UI, but it would really be great if it were integrated.